Flexible display device and method for fabricating the same

ABSTRACT

A display device includes a first substrate including an active area, a bending area, and a pad area; a plurality of pixels to display an image in the active area, each of the plurality of pixels including an organic light emitting diode (OLED); a signal line and a power line disposed on the first substrate, the signal line and the power ling being disposed on a same layer in the bending area, the bending area on the first substrate being configured to be bent flexibly; and a second substrate facing the active area and disposed on the first substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending U.S. patent applicationSer. No. 14/572,232 filed on Dec. 16, 2014, which claims the benefitunder 35 U.S.C. §119(a) to Korean Patent Application No. 10-2013-0169271filed on Dec. 31, 2013, all of which are hereby expressly incorporatedby reference into the present application.

BACKGROUND OF THE DISCLOSURE Field of the Invention

The present disclosure relates to a flexible display device, andparticularly, to a flexible display device capable of preventingdisconnection or short-circuiting of wires that may occur at a bendingarea during a bending process for a minimized bezel width, in an organiclight-emitting diode display manufactured using a flexible substrate,and a method for fabricating the same.

Discussion of the Related Art

Among flat panel display devices proposed to replace the conventionalcathode ray tube, an organic light-emitting diode (OLED) display has acharacteristic that a light-emitting diode provided at a display panelhas high brightness and a low operation voltage. Such OLED display hasadvantages that a contrast ratio is large because it is a spontaneouslight-emission type, and a very thin display can be implemented. TheOLED display can easily implement moving images because a response timeis several micro seconds (μs). Further, the OLED display has anunlimited viewing angle, and is stably operated even at a lowtemperature.

In the OLED display device, display devices are formed on a substratesuch as glass. Recently, a flexible organic light-emitting diode (OLED)display device, which is capable of maintaining a display function evenwhen rolled (or bent) like paper due to its flexible material such asplastic or metal foil rather than a non-flexible substrate, has beendeveloped.

FIG. 1 is a planar view schematically illustrating a flexible organiclight-emitting diode (OLED) display device in accordance with theconventional art, and FIG. 2A is an enlarged view of part ‘A’ in FIG. 1.

Referring to FIGS. 1 and 2A, the conventional flexible OLED displaydevice 1 is formed on a flexible substrate 10 including an active area(A/A) and a non-active area (N/A).

The active area (A/A) is a region where an image is substantiallydisplayed. A plurality of pixels (P) are arranged in the active area(A/A), in the form of matrices. Each of the pixels (P) includes aswitching transistor (ST1), a driving transistor (DT), a sensingtransistor (ST2), a capacitor (C), and an organic light-emitting diode(OLED).

The switching transistor (ST1) of the pixel (P) is connected to a gateline (GL) and a data line (DL) which are formed in the active area (A/A)so as to cross each other. The driving transistor (DT) is connected to adriving voltage line 14 b for supplying a driving voltage (VDD) to thepixel (P) in the active area (A/A). The sensing transistor (ST2) isconnected to a reference voltage line 14 a for supplying a referencevoltage (Vref) to the pixel (P) in the active area (A/A).

The non-active area (N/A) is a region formed around the active area(A/A), and is covered by a bezel portion, etc. Driving circuitry fordriving the pixels (P) in the active area (A/A) and wires may be formedin the non-active area (N/A).

The driving circuitry includes a data driving portion 20, a gate drivingportion 13 and a light-emitting controller (not shown). The data drivingportion 20 is mounted at a lower end non-active area (N/A) in the formof a chip. The gate driving portion 13 and the light-emitting controllerare formed at one or more sides of the non-active area (N/A), in theform of a gate in panel (GIP).

Wires include power lines 14 a-14 c, and signal lines GSL, DSL. Thepower lines 14 a-14 c includes a driving voltage line 14 a, a referencevoltage line 14 b and a ground line 14 c. Also, the signal lines GSL,DSL include a gate signal line (GSL), a data signal line (DSL) and alight-emitting signal line (not shown).

The driving voltage line 14 a outputs a driving voltage (VDD) providedfrom the data driving portion 20 to the pixel (P) in the active area(A/A). The reference voltage line 14 b outputs a reference voltage(Vref) provided from the data driving portion 20 to the pixel (P) in theactive area (A/A). The ground line 14 c outputs a ground voltage (GND)provided from the data driving portion 20 to the pixel (P) in the activearea (A/A).

The driving voltage line 14 a, the reference voltage line 14 b and theground line 14 c include a region vertically extending from the datadriving portion in the lower end non-active area (N/A), and a regionformed in parallel to the data driving portion 20.

That is, the driving voltage line 14 a, the reference voltage line 14 band the ground line 14 c are extending from the data driving portion 20in a vertical direction, at a region adjacent to the data drivingportion 20 in the lower end non-active area (N/A). The driving voltageline 14 a, the reference voltage line 14 b and the ground line 14 c areformed as bars, in parallel to the data driving portion 20, at a regionadjacent to the active area (A/A) in the lower end non-active area(N/A).

The gate signal line (GSL) outputs a gate signal provided from the datadriving portion 20 to the gate driving portion 13. The data signal line(DSL) outputs a data signal provided from the data driving portion 20 tothe data line (DL) in the active area (A/A). The light-emitting signalline outputs a light-emitting signal provided from the data drivingportion 20 to the light-emitting controller.

In accordance with one embodiment, these wires may be formed to crosseach other at least once, in the lower end non-active area (N/A). Thus,the power lines 14 a-14 c and the signal lines GSL, DSL are formed ondifferent layers, in order to prevent short-circuiting when the wirescross each other.

In the conventional flexible OLED display device 1, the lower endnon-active area (N/A) is formed to have a larger width than the rest ofthe non-active area (N/A). A bending area (B/A) is formed in the lowerend non-active area (N/A), and part of the lower end non-active area(N/A) is bent to a rear surface of the flexible OLED display device 1.Under such configuration, the width of the lower end non-active area(N/A) can be reduced.

FIG. 2B is a cross-sectional view of the flexible OLED display device ofFIG. 1, which illustrates a bent state.

Referring to FIG. 2B, reference numeral 11 denotes an organiclight-emitting diode (OLED) formed in an active area (A/A), andreference numeral 12 denotes an encapsulation layer for encapsulating anOLED.

Referring to FIG. 2B, in the conventional flexible OLED display device1, the lower end non-active area (N/A) is bent based on a bending area(B/A), so that part of the lower end non-active area (N/A) can bepositioned on a rear surface of the flexible OLED display device 1. Acurvature radius (R) of the bending area (B/A) is about 0.3 mm.

As mentioned above with reference to FIG. 2A, in the lower endnon-active area (N/A) of the conventional flexible OLED display device1, wires are formed to cross each other. Thus, the power lines 14 a-14 cand the signal lines GSL, DSL are formed on different layers.

However, because the wires are formed to cross each other even in thebending area (B/A), the wires may be disconnected from each other due tobending stress in the bending area (B/A).

FIG. 3 is a cross-sectional view taken along line in FIG. 2B.

Referring to FIG. 3, the signal lines GSL, DSL and the power lines 14a-14 c are formed on different layers to thus be insulated from eachother.

For instance, a gate signal line (GSL) and a data signal line (DSL) areformed on a flexible substrate 10 with a distance therebetween. A firstinsulating layer 15 is formed on the gate signal line (GSL) and the datasignal line (DSL).

A driving voltage line 14 a and a ground line 14 c are formed on thefirst insulating layer 15 with a predetermined gap therebetween. Thedriving voltage line 14 a and the ground line 14 c are formed to overlapthe gate signal line (GSL) and the data signal line (DSL), respectively.A second insulating layer 16 is formed on the driving voltage line 14 aand the ground line 14 c.

When the bending area (B/A) is bent with more than a predeterminedcurvature radius, cracks/breaks may occur at wires due to bending stressas shown in FIG. 3 (indicated by “a” and “b”). This may cause the wiresto be disconnected from each other, or the insulating layer may bedamaged to cause short-circuiting of the wires.

Such disconnection or short-circuiting of the wires may cause amalfunction of the flexible OLED display device 1.

SUMMARY OF THE DISCLOSURE

Therefore, an aspect of the detailed description is to provide aflexible display device capable of preventing disconnection orshort-circuiting of wires, by forming wires in a bending area of anon-active area, on the same layer so as not to cross each other, and amethod for fabricating the same.

To achieve these and other advantages and in accordance with the purposeof this specification, as embodied and broadly described herein, thereis provided a flexible display device, including: a flexible substratehaving an active area where pixels provided with organic light-emittingdiodes have been formed, a non-active area formed around the activearea, and a bending area formed at a lower part of the non-active area;a data driving portion mounted in the lower end non-active area; aplurality of power lines formed in the lower end non-active area, andconfigured to supply power signals provided from the data drivingportion to the active area; and a plurality of signal lines formed inthe lower end non-active area, and configured to supply driving signalsprovided from the data driving portion to the active area, wherein theplurality of power lines and the plurality of signal lines are formed inthe bending area, on the same layer in parallel to each other.

To achieve these and other advantages and in accordance with the purposeof this specification, as embodied and broadly described herein, thereis also provided a method for fabricating a flexible display device, themethod including: preparing a substrate having an active area, anon-active area, and a bending area formed at a lower part of thenon-active area; forming a thin film transistor and an organiclight-emitting diode on the active area of the substrate; and forming aplurality of power lines and a plurality of signal lines connected tothe active area, on the lower end non-active area of the substrate,wherein the plurality of power lines and the plurality of signal linesare formed in the bending area on the same layer in parallel to eachother.

The present invention can have the following advantages.

In the bending area of the non-active area, wires are formed on the samelayer in parallel to each other, so as not to overlap or cross eachother. As a result, disconnection or short-circuit of the wires, whichoccurs when the bending area is bent, can be prevented. Thus amalfunction of the flexible display device can be prevented.

Further scope of applicability of the present application will becomemore apparent from the detailed description given hereinafter. However,it should be understood that the detailed description and specificexamples, while indicating preferred embodiments of the disclosure, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the disclosure will becomeapparent to those skilled in the art from the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments andtogether with the description serve to explain the principles of thedisclosure.

In the drawings:

FIG. 1 is a planar view schematically illustrating a flexible organiclight-emitting diode (OLED) display device in accordance with therelated art;

FIG. 2A is an enlarged view of part ‘A’ in FIG. 1;

FIG. 2B is a cross-sectional view of the flexible OLED display device ofFIG. 1, which illustrates a bent state;

FIG. 3 is a cross-sectional view taken along line in FIG. 2B;

FIG. 4 is a planar view of a flexible OLED display device according to afirst embodiment of the present invention;

FIG. 5 is an equivalent circuit diagram for a single pixel in theflexible OLED display device of FIG. 4;

FIG. 6 is a cross-sectional view taken along line VIa≠VIa′ and VIb˜VIb′in the flexible OLED device of FIG. 4;

FIGS. 7A to 7C are views illustrating processes of fabricating aflexible OLED display device according to the first embodiment of thepresent invention;

FIG. 8 is a planar view of a flexible OLED display device according to asecond embodiment of the present invention;

FIG. 9 is a cross-sectional view taken along line VII˜VII′ in theflexible OLED display device of FIG. 8;

FIG. 10 is a view illustrating a wire structure in a bending area in aflexible OLED display device according to the present invention; and

FIG. 11 is a view illustrating various embodiments of FIG. 10.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Description will now be given in detail of the exemplary embodiments ofthe present invention, with reference to the accompanying drawings. Forthe sake of brief description with reference to the drawings, the sameor equivalent components will be provided with the same referencenumbers, and description thereof will not be repeated.

Hereinafter, a flexible display device and a method for fabricating thesame according to the present invention will be explained in moredetail.

FIG. 4 is a planar view of a flexible organic light-emitting diode(OLED) display device according to a first embodiment of the presentinvention.

Referring to FIG. 4, the flexible OLED display device 100 according to afirst embodiment of the present invention may be formed on a flexiblesubstrate 110 including an active area (display area) (A/A) and anon-active area (non-display area) (N/A).

The active area (A/A) is a region where an image is substantiallydisplayed. On the active area (A/A), a plurality of gate lines (GL) anda plurality of data lines (DL) may be formed to cross each other,thereby defining pixel regions. A plurality of sensing lines (SL) may beformed in parallel to the plurality of gate lines (GL).

Power lines for supplying a driving voltage (VDD), a reference voltage(Vref) and a ground voltage (GND) to pixel regions, e.g., a drivingvoltage line 146 b, a reference voltage line 147 b and a ground line 145b may be formed in the active area (A/A).

A pixel (P) having a plurality of switching devices may be formed at thepixel region. The pixel (P) may operate by being connected to each ofthe gate line (GL), the data line (DL) and the sensing line (SL).

FIG. 5 is an equivalent circuit diagram for a single pixel in theflexible OLED display device of FIG. 4.

Referring to FIGS. 4 and 5, the pixel (P) in the active area (A/A) mayhave a structure where three switching devices (ST1, DT, ST2), onecapacitor (C) and one organic light emitting diode (OLED) are formed.However, the present invention is not limited to this configuration.That is, the pixel (P) may be formed to have various structures such as2T1C, 4T1C, 5T1C and 6T1C.

The switching devices (ST1, DT, ST2) may include a switching transistor(ST1), a driving transistor (DT) and a sensing transistor (ST2). Theswitching device (ST1, DT, ST2) may be thin film transistors (TFT), forexample, formed of amorphous silicon or poly-crystalline silicon.

The switching transistor (ST1) of the pixel (P) may include a gateelectrode connected to the gate line (GL) of the active area (A/A), asource electrode connected to the data line (DL), and a drain electrodeconnected to the driving transistor (DT). The switching transistor (ST1)may output a data signal supplied from the data line (DL) to the drivingtransistor (DT), according to a gate signal supplied from the gate line(GL).

The driving transistor (DT) of the pixel (P) may include a gateelectrode connected to the drain electrode of the switching transistor(ST1), a source electrode connected to an OLED, and a drain electrodeconnected to driving voltage lines 146 a, 146 b for supplying a drivingvoltage (VDD). The driving transistor (DT) may control the size ofcurrent applied to the OLED from the driving voltage (VDD), according toa data signal supplied from the switching transistor (ST1).

The capacitor (C) of the pixel (P) may be connected between the gateelectrode of the driving transistor (DT) and the OLED. The capacitor (C)may store therein a voltage corresponding to a data signal supplied tothe gate electrode of the driving transistor (DT). Also, the capacitor(C) may constantly maintain an ‘ON’ state of the driving transistor (DT)for a single frame, with the voltage stored therein.

The sensing transistor (ST2) of the pixel (P) may include a gateelectrode connected to the sensing line (SL), a source electrodeconnected to the source electrode of the driving transistor (DT), and adrain electrode connected to reference voltage lines 147 a, 147 b forsupplying a reference voltage (Vref). The sensing transistor (ST2) maysense a threshold voltage (Vth) of the driving transistor (DT), therebypreventing a malfunction of the OLED.

The switching transistor (ST1) of the pixel (P) may be turned on by agate signal supplied to the gate line (GL), and the capacitor (C) of thepixel (P) may be charged with charges by a data signal supplied to thedata line (DL). The amount of current applied to the channel of thedriving transistor (DT) may be determined according to a potentialdifference between a voltage charged at the capacitor (C) and thedriving voltage (VDD). The amount of light emitted from the OLED may bedetermined based on such amount of current. As the OLED emits light, animage is displayed.

The sensing transistor (ST2) may be turned on earlier than the switchingtransistor (ST1), according to a sensing signal supplied through thesensing line (SL). Under such configuration, electroluminescence of theOLED by the driving voltage (EVDD), which occurs before a data signal ischarged at the capacitor (C) during an initial operation of theswitching transistor (ST1), can be prevented.

Referring back to FIG. 4, the non-active area (N/A) of the flexible OLEDdisplay device 100 may be formed adjacent, for example, around theactive area (A/A). Driving circuitry for driving the pixels (P) in theactive area (A/A) and wires may be formed in the non-active area (N/A).

The driving circuitry may include a data driving portion 230, a gatedriving portion 210 and a light-emitting controller 220.

The data driving portion 230 may be mounted at the non-active area (N/A)below the active area (A/A), in the form of a chip. The data drivingportion 230 may generate a data signal by receiving a signal from anexternal printed circuit board (not shown). The generated data signalsmay be output to the plurality of data lines (DL) in the active area(A/A) through wires.

The data driving portion 230 may output a gate signal and alight-emitting signal provided from external circuitry, to the gatedriving portion 210 and the light-emitting controller 220 through wires,respectively. The data driving portion 230 may output power signalsprovided from external circuitry, e.g., power signals including adriving voltage (VDD), a reference voltage (Vref), a ground voltage(GND), etc., to driving voltage lines 146 a, 146 b, reference voltagelines 147 a, 147 b, and ground lines 145 a, 145 b, respectively.

The gate driving portion 210 may be formed at one side of the non-activearea (N/A) outside the active area (A/A), in the form of a gate in panel(GIP). The gate driving portion 210 may sequentially output gate signalsprovided from the data driving portion 230 through wires (e.g., gatesignal lines 141 a), to the plurality of gate lines (GL) in the activearea (A/A).

The light-emitting controller 220 may be formed at another side of thenon-active area (N/A) outside the active area (A/A), in the form of agate in panel (GIP) so as to correspond to the gate driving portion 210.The light-emitting controller 220 may sequentially output light-emittingsignals provided from the data driving portion 230 through wires (e.g.,light-emitting lines 141 c), to the plurality of sensing lines (SL) inthe active area (A/A).

The wires may include power lines and signal lines formed between thedata driving portion 230 and the active area (A/A). The power lines mayinclude driving voltage lines 146 a, 146 b, reference voltage lines 147a, 147 b, and ground lines 145 a, 145 b. Also, the signal lines mayinclude a gate signal line 141 a, a data signal line 141 b, and alight-emitting signal line 141 c.

The power lines may supply power signals provided from the data drivingportion 230, to the active area (A/A). The signal lines may supplydriving signals provided from the data driving portion 230, e.g., a gatesignal, a data signal and a light-emitting signal, to the active area(A/A), the gate driving portion 210 and the light-emitting controller220.

The driving voltage lines 146 a, 146 b may be formed in the lower endnon-active area (N/A), and may output a driving voltage (VDD) providedfrom the data driving portion 230 to the pixel (P) in the active area(A/A).

The driving voltage lines 146 a, 146 b may include a first drivingvoltage line 146 a and a second driving voltage line 146 b. The firstdriving voltage line 146 a connected to the data driving portion 230.The second driving voltage line 146 b may be connected to the firstdriving voltage line 146 a and formed as a bar in a direction parallelto the data driving portion 230. The second driving voltage line 146 bmay be formed such that one side thereof is connected to the firstdriving voltage line 146 a, and another side thereof is extending to thepixel (P) in the active area (A/A). Based on this configuration, thesecond driving voltage line 146 b may output a driving voltage (VDD)provided through the first driving voltage line 146 a to each pixel (P).

The reference voltage lines 147 a, 147 b may be formed in the lower endnon-active area (N/A), and may output a reference voltage (Vref)provided from the data driving portion 230 to the pixel (P) in theactive area (A/A).

The reference voltage lines 147 a, 147 b may include a first referencevoltage line 147 a and a second reference voltage line 147 b. The firstreference voltage line 147 a connected to the data driving portion 230.The second reference voltage line 147 b may be connected to the firstreference voltage line 147 a and formed as a bar in parallel to thesecond driving voltage line 146 b. The second reference voltage line 147b may be formed such that one side thereof is connected to the firstreference voltage line 147 a, and another side thereof is extending tothe pixel (P) in the active area (A/A). Based on this configuration, thesecond reference voltage line 147 b may output a reference voltage(Vref) provided through the first reference voltage line 147 a to eachpixel (P).

The ground lines 145 a, 145 b may be formed in the lower end non-activearea (N/A), and may output a ground voltage (GND) provided from the datadriving portion 230 to the pixel (P) in the active area (A/A).

The ground lines 145 a, 145 b may include a first ground line 145 a anda second ground line 145 b. The first ground line 145 a connected to thedata driving portion 230. The second ground line 145 b may be connectedto the first ground line 145 a, and formed as a bar in parallel to thesecond driving voltage line 146 b and the second reference voltage line147 b. The second ground line 145 b may be formed such that one sidethereof is connected to the first ground line 145 a, and another sidethereof is extending to the pixel (P) in the active area (A/A). By thisconfiguration, the second ground line 145 b may output a ground voltage(GND) provided through the first ground line 145 a to each pixel (P).

The gate signal line 141 a may be formed between the data drivingportion 230 and the gate driving portion 210 in the lower end non-activearea (N/A). The gate signal line 141 a may output a gate signal providedfrom the data driving portion 230 to the gate driving portion 210. Thegate signal may be output to the plurality of gate lines (GL) in theactive area (A/A), through the gate driving portion 210.

The data signal line 141 b may be formed in the lower end non-activearea (N/A), between the data driving portion 230 and the data line (DL)in the active area (A/A). The data signal line 141 b may output a datasignal provided from the data driving portion 230 to the plurality ofdata lines (DL) in the active area (A/A).

The light-emitting signal line 141 c may be formed in the non-activearea (N/A) between the data driving portion 230 and the light-emittingcontroller 220. The light-emitting signal line 141 c may output alight-emitting signal provided from the data driving portion 230, to thelight-emitting controller 220. The light-emitting signal may be outputto the plurality of sensing lines (SL) in the active area (A/A), by thelight-emitting controller 220.

In the flexible OLED display device 100 according to this embodiment ofthe present invention, the lower end non-active area (N/A) may include abending area (B/A). The bending area (B/A) may be a region which has apredetermined curvature when part of the lower end non-active area (N/A)is bent to the rear or front surface of the flexible OLED display device100. That is, the bending area (B/A) is a flexible portion includingflexible materials that is provided between one end of the displaydevice 100 and the other part of the device 100 and allows the one endto be bent or rotated around the bending area (B/A) toward the front orrear surface of the other part. In accordance with one embodiment, thelower end non-active area (N/A) may be bent around the bending area(B/A) toward the front or rear surface of the flexible OLED displaydevice 100. As an example, the lower end non-active area (N/A) may beattached to the rear surface of the flexible OLED display device 100 bythe rotation around the bending area (B/A). Although FIG. 4 shows onlyone bending area formed adjacent one end of the flexible OLED displaydevice 100, it will be readily appreciable to one skilled in the artthat the bending area (B/A) may be formed adjacent any side of theflexible OLED display device 100 (e.g. 4 bending areas formed adjacent 4sides of the flexible OLED display device 100 in rectangular shape).

The lower end non-active area (N/A) may be divided into three regions bythe bending area (B/A). For instance, the lower end non-active area(N/A) may be divided into a first area between the bending area (B/A)and the active area (A/A), the bending area (B/A), and a second areabetween the bending area (B/A) and an area where the data drivingportion 230 has been mounted.

The first area of the lower end non-active area (N/A) may be a regioncovered by a bezel portion, etc., together with the rest of thenon-active area (N/A). Also, the second area may be a region that may bepositioned on a rear surface of the flexible OLED display device 100, bybending of the bending area (B/A).

Power lines, which include the second driving voltage line 146 b, thesecond reference voltage line 147 b and the second ground line 145 b,may be formed in the first area of the lower end non-active area (N/A).

Signal lines, which include the gate signal line 141 a, the data signalline 141 b and the light-emitting signal line 141 c, may be formed inthe first area so as to cross the power lines. The signal lines and thepower lines in the first area may be formed to overlap each other atdifferent layers on the flexible substrate 110.

Power lines, which include the first driving voltage line 146 a, thefirst reference voltage line 147 a and the first ground line 145 a, maybe formed in the bending area (B/A) of the lower end non-active area(N/A).

Signal lines, which include the gate signal line 141 a, the data signalline 141 b and the light-emitting signal line 141 c, may be formed inthe bending area (B/A) in parallel to the power lines so as not to crossthe power lines. The signal lines and the power lines in the bendingarea (B/A) may be formed to be spaced from each other on the same layeron the flexible substrate 110.

The power lines, which include the first driving voltage line 146 a, thefirst reference voltage line 147 a and the first ground line 145 a, maybe formed in the second area of the lower end non-active area (N/A).

The signal lines, which include the gate signal line 141 a, the datasignal line 141 b and the light-emitting signal line 141 c, may beformed in the second area in parallel to the power lines so as not tocross the power lines. The signal lines and the power lines may beformed to be extending from the data driving portion 230 in parallel toeach other. In this case, the signal lines and the power lines may beformed to be in parallel to each other by being bent at least twice inthe second area. The signal lines and the power lines in the second areamay be formed to be spaced from each other on the same layer.

As mentioned above, in the flexible OLED display device 100 according tothis embodiment, wires are formed on the same layer in parallel to eachother, in the bending area (B/A) of the lower end non-active area (N/A)where bending is performed. Accordingly, unlike in the conventional art,the occurrence of disconnection of the wires due to bending stress canbe prevented.

In the second area and the bending area (B/A) of the lower endnon-active area (N/A), wires are formed on the same layer. However, inthe first area, wires are formed on different layers. By suchconfiguration, wires formed in the bending area (B/A) may be connectedto wires formed on different layers in the first area, through holes(not shown).

FIG. 6 is a cross-sectional view taken along line VIa˜VIa′ and VIb˜VIb′in the flexible OLED device of FIG. 4.

Referring to FIGS. 4 and 6, the flexible OLED display device 100 mayinclude pixels (P) formed in the active area (A/A), and wires formed inthe non-active area (N/A) (e.g., lower end non-active area (N/A)). Thelower end non-active area (N/A) where wires have been formed may be thebending area (B/A).

A thin film transistor (TFT) and an organic light emitting diode (OLED)may be formed on the flexible substrate 110 in the active area (A/A).

For instance, a passivation layer 111 may be formed on the entiresurface of the flexible substrate 110. A semiconductor layer 121 formedof amorphous or poly-crystalline silicon may be formed on thepassivation layer 111.

A gate insulating layer 113 may be formed on the semiconductor layer121, and a gate electrode 123 may be formed on the gate insulating layer113 at a position corresponding to a predetermined region of thesemiconductor layer 121.

An interlayer insulating layer 115 may be formed on the gate electrode123, and a source electrode 125 a and a drain electrode 125 b may beformed on the interlayer insulating layer 115.

The source electrode 125 a and the drain electrode 125 b may beconnected to the semiconductor layer 121, through contact holes (notshown) formed at the interlayer insulating layer 115 and the gateinsulating layer 113.

The semiconductor layer 121, the gate electrode 123, the sourceelectrode 125 a and the drain electrode 125 b may constitute a thin filmtransistor in the active area (A/A) of the flexible substrate 110. TheTFT may be, for example, a driving transistor of the flexible OLEDdisplay device 100. However, the present invention is not limited tothis example.

A planarization layer 117 may be formed on the TFT. A first electrode131, connected to the drain electrode 125 b through a contact hole (notshown), may be formed on the planarization layer 117.

A pixel defining layer 130, through which part of the first electrode131 is exposed to the outside, may be formed on the first electrode 131.A light-emitting layer 133 may be formed on the pixel defining layer130. The light-emitting layer 133 may be formed on the first electrode131 which has been exposed to the outside by the pixel defining layer130. A second electrode 135 may be formed on the light-emitting layer133.

The first electrode 131, the light-emitting layer 133 and the secondelectrode 135 may constitute an OLED in the active area (A/A) of theflexible substrate 110.

Signal lines and power lines may be formed on the flexible substrate 110in the bending area (B/A). The signal lines may include the gate signalline 141 a and the data signal line 141 b. The power lines may includethe first ground line 145 a and the first driving voltage line 146 a.

For instance, the passivation layer 111 may be formed on the entiresurface of the flexible substrate 110. The gate signal line 141 a, thedata signal line 141 b, the first ground line 145 a and the firstdriving voltage line 146 a may be formed commonly on the passivationlayer 111, such that they are spaced from each other with apredetermined distance therebetween, for example, in parallel to eachother.

In accordance with one embodiment, the signal lines and the power linesformed in the bending area (B/A) may be formed of the same metallicmaterial as the source electrode 125 a and the drain electrode 125 bformed in the active area (A/A), at the same processing stage.

Like in the active area (A/A), the planarization layer 117 may be formedas an insulating layer on the signal lines and the power lines formed inthe bending area (B/A).

As mentioned above, in the flexible OLED display device 100 according toone embodiment, wires may be formed on the same layer in the bendingarea (B/A), with the same metallic material. Accordingly, even if theplanarization layer 117 is damaged by bending stress in the bending area(B/A), the wires in the bending area (B/A) are not disconnected orcracked. This can prevent a malfunction of the flexible OLED displaydevice 100.

FIGS. 7A to 7C are views illustrating processes of fabricating aflexible OLED display device according to the first embodiment of thepresent invention.

A passivation layer 111 may be formed on the entire surface of asubstrate divided into an active area (A/A) and a non-active area (N/A),e.g., a glass substrate 101. The passivation layer 111 is provided sothat thin film transistors, organic light-emitting diodes and wires canbe prevented from being damaged during the process of detaching theglass substrate 101, as described below in more detail.

The non-active area (N/A) may include a bending area (B/A) formed belowthe active area (A/A), i.e., a bending area (B/A) of a lower endnon-active area (N/A).

Amorphous silicon or poly-crystalline silicon is deposited in the activearea (A/A) on the glass substrate 101 where the passivation layer 111has been formed. Then the amorphous silicon or the poly-crystallinesilicon is selectively patterned, thereby forming a semiconductor layer121. The semiconductor layer 121 may include a source region and a drainregion each including impurities, and a channel region including noimpurities.

A gate insulating layer 113 may be formed on the entire surface of theglass substrate 101 where the semiconductor layer 121 has been formed.The gate insulating layer 113 may be formed as a silicon oxide film(SiOx), a silicon nitride film (SiNx), or a multi-layer thereof.

The gate insulating layer 113 may not be formed in the non-active area(N/A) of the glass substrate 101.

A gate electrode 123 may be formed on the gate insulating layer 113, ata position corresponding to a channel region of the semiconductor layer121. The gate electrode 123 may be formed by depositing a metallicmaterial such as molybdenum (Mo), aluminum (Al), chrome (Cr), titanium(Ti) and copper (Cu), or an alloy thereof, on the gate insulating layer113, and then by selectively patterning the metallic material or thealloy.

An interlayer insulating layer 115 may be formed on the entire surfaceof the active area (A/A) of the glass substrate 101 where the gateelectrode 123 has been formed. The interlayer insulating layer 115 maybe formed as a silicon oxide film (SiOx), a silicon nitride film (SiNx),or a multi-layer thereof.

Contact holes (not shown) may be formed by etching part of theinterlayer insulating layer 115 and the gate insulating layer 113,thereby exposing part of the semiconductor layer 121, e.g., a sourceregion and a drain region to the outside therethrough.

A source electrode 125 a and a drain electrode 125 b may be formed onthe interlayer insulating layer 115. The source electrode 125 a may beformed so as to be connected to the source region of the semiconductorlayer 121 through the contact hole, and the drain electrode 125 b may beformed so as to be connected to the drain region of the semiconductorlayer 121 through the contact hole.

The source electrode 125 a and the drain electrode 125 b may be formedby depositing a metallic material such as Ti, Al and Mo, or an alloythereof such as Ti/Al/Ti and Mo/Al, on the interlayer insulating layer115, and then by selectively patterning the metallic material or thealloy.

A thin film transistor (TFT) including the semiconductor layer 121, thegate electrode 123, the source electrode 125 a and the drain electrode125 b, which is, e.g., a driving transistor of the flexible OLED displaydevice 100, may be formed in the active area (A/A) of the glasssubstrate 101.

Wires, e.g., a gate signal line 141 a, a data signal line 141 b, a firstground line 145 a and a first driving voltage line 146 a may be formedon the passivation layer 111, in the non-active area (N/A) of the glasssubstrate 101. Such wires may be formed on the passivation layer 111 soas to be spaced from each other with a predetermined interval.

The gate signal line 141 a, the data signal line 141 b, the first groundline 145 a and the first driving voltage line 146 a may be formed of thesame metallic material as the source electrode 125 a and the drainelectrode 125 b, at the same processing stage.

Referring to FIG. 7B, a planarization layer 117 may be formed on theentire surface of the active area (A/A) where a thin film transistor hasbeen formed, and the non-active area (N/A) where wires have been formed.

The planarization layer 117 may be formed by a spin coating method, forexample, the method for coating an organic material or an inorganicmaterial such as polyimide, benzocyclobutene series resin and acrylate,in the form of a liquid phase, and then hardening the material.

A contact hole (not shown) may be formed by etching part of theplanarization layer 117 in the active area (A/A), thereby exposing thedrain electrode 125 b to the outside therethrough.

A first electrode 131 may be formed on the planarization layer 117 inthe active area (A/A). The first electrode 131 may be connected to thedrain electrode 125 b through the contact hole of the planarizationlayer 117.

The first electrode 131 may be formed of a transparent conductivematerial such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide) or ZnO(Zinc Oxide), which may form the anode of an OLED.

A pixel defining layer 130 may be formed on the first electrode 131. Thepixel defining layer 130 may have an opening through which part of thefirst electrode 131 is exposed to the outside, and may define a pixelregion.

The pixel defining layer 130 may be formed by a spin coating method, forexample, the method for coating an organic material or an inorganicmaterial such as polyimide, benzocyclobutene series resin and acrylate,in the form of a liquid phase, and then hardening the material.

Referring to FIGS. 7B and 7C, a light-emitting layer 133 may be formedon the pixel defining layer 130. The light-emitting layer 133 may beformed on the opening of the pixel defining layer 130, i.e., may beformed on the first electrode 131 exposed to the outside by the pixeldefining layer 130.

A second electrode 135 may be formed on the light-emitting layer 133.The second electrode 135 may be formed of aluminum (Al), silver (Ag),magnesium (Mg), or an alloy thereof by deposition.

An OLED including the first electrode 131, the light-emitting layer 133and the second electrode 135 may be formed on a TFT of the glasssubstrate 101 in the active area (A/A).

When a TFT and an OLED have been formed in the active area (A/A) andwires have been formed in the non-active area (N/A), the glass substrate101 may be detached from the passivation layer 111. Then, a flexiblesubstrate 110 may be attached to the passivation layer 111.

The flexible substrate 110 may have the same active area (A/A) andnon-active area (N/A) as the glass substrate 101.

The flexible substrate 110 may be formed, for example, of one ofpolycarbon, polyimide, polyether sulfone (PES), polyarylate,polyethylene naphthalate (PEN) or poly ethyleneterephthalate (PET).

The glass substrate 101 may be detached from the passivation layer 111through irradiation of laser, etc., and the flexible substrate 110 maybe attached to the passivation layer 111 by an adhesive tape such as anoptically clear adhesive (OCA), with reference to FIG. 7C.

FIG. 8 is a planar view of a flexible OLED display device according to asecond embodiment of the present invention.

Referring to FIG. 8, the flexible OLED display device according to thesecond embodiment may be formed on a flexible substrate 110 having anactive area (A/A) and a non-active area (N/A).

The active area (A/A) is a region where an image is substantiallydisplayed. On the active area (A/A), a plurality of gate lines (GL) anda plurality of data lines (DL) may be formed to cross each other,thereby defining pixel regions. A plurality of sensing lines (SL) may beformed in parallel to the plurality of gate lines (GL).

Power lines for supplying a driving voltage (VDD), a reference voltage(Vref) and a ground voltage (GND) to pixel regions, e.g., a drivingvoltage line 146 b, a reference voltage line 147 b and a ground line 145b may be formed in the active area (A/A).

A pixel (P) having a plurality of switching devices may be formed at thepixel region. The pixel (P) may be the same pixel as described abovewith reference to FIG. 5.

The non-active area (N/A) of the flexible OLED display device 200 may beformed around the active area (A/A), which may be defined by the dottedline. Driving circuitry for driving the pixels (P) in the active area(A/A) and wires may be formed in the non-active area (N/A).

The driving circuitry may include a data driving portion 230, a gatedriving portion 210 and a light-emitting controller 220.

The data driving portion 230 may be mounted in the non-active area (N/A)positioned below the active area (A/A), i.e., the lower-end non-activearea (N/A). The gate driving portion 210 and the light-emittingcontroller 220 may be formed in the non-active area (N/A), i.e., at twosides outside the active area (A/A), in the form of a gate in panel(GIP).

The data driving portion 230 may generate a data signal by receiving asignal from an external circuit. The generated data signal may be outputto the plurality of data lines (DL) in the active area (A/A) throughwires. The gate driving portion 210 may output a gate signal providedfrom the data driving portion 230, to the plurality of gate lines (GL)in the active area (A/A), through wires. The light-emitting controller220 may output a light-emitting signal provided from the data drivingportion 230, to the plurality of sensing lines (SL) in the active area(A/A), through wires.

Wires may include power lines including driving voltage lines 146 a, 146b, reference voltage lines 147 a, 147 b, and ground lines 145 a, 145 b,and signal lines including a gate signal line 141 a, a data signal line141 b, and a light-emitting signal line 141 c.

The driving voltage lines 146 a, 146 b may be formed in the lower endnon-active area (N/A), and may output a driving voltage (VDD) providedfrom the data driving portion 230 to the pixel (P) in the active area(A/A).

The driving voltage lines 146 a, 146 b may include a first drivingvoltage line 146 a and a second driving voltage line 146 b. The firstdriving voltage line 146 a connected to the data driving portion 230.The second driving voltage line 146 b may be connected to the firstdriving voltage line 146 a, and formed as a bar in a direction parallelto the data driving portion 230. The second driving voltage line 146 bmay be formed such that one side thereof is connected to the firstdriving voltage line 146 a, and another side thereof is extending to thepixel (P) in the active area (A/A). Based on this configuration, thesecond driving voltage line 146 b may output a driving voltage (VDD)provided through the first driving voltage line 146 a to each pixel (P).

The reference voltage lines 147 a, 147 b may be formed in the lower endnon-active area (N/A), and may output a reference voltage (Vref)provided from the data driving portion 230 to the pixel (P) in theactive area (A/A).

The reference voltage lines 147 a, 147 b may include a first referencevoltage line 147 a and a second reference voltage line 147 b. The firstreference voltage line 147 a connected to the data driving portion 230.The second reference voltage line 147 b may be connected to the firstreference voltage line 147 a, and formed as a bar in parallel to thesecond driving voltage line 146 b. The second reference voltage line 147b may be formed such that one side thereof is connected to the firstreference voltage line 147 a, and another side thereof is extending tothe pixel (P) in the active area (A/A). Based on this configuration, thesecond reference voltage line 147 b may output a reference voltage(Vref) provided through the first reference voltage line 147 a to eachpixel (P).

The ground lines 145 a, 145 b may be formed in the lower end non-activearea (N/A), and may output a ground voltage (GND) provided from the datadriving portion 230 to the pixel (P) in the active area (A/A).

The ground lines 145 a, 145 b may include a first ground line 145 a anda second ground line 145 b. The first ground line 145 a may be connectedto the data driving portion 230. Further, the second ground line 145 bmay be connected to the first ground line 145 a, and formed as a bar ina direction parallel to the second driving voltage line 146 b and thesecond reference voltage line 147 b. The second ground line 145 b may beformed such that one side thereof is connected to the first ground line145 a, and another side thereof is extending to the pixel (P) in theactive area (A/A). Based on this configuration, the second ground line145 b may output a ground voltage (GND) provided through the firstground line 145 a to each pixel (P).

The gate signal line 141 a may be formed in the lower end non-activearea (N/A), between the data driving portion 230 and the gate drivingportion 210. The gate signal line 141 a may output a gate signalprovided from the data driving portion 230 to the gate driving portion210. The gate signal may be output to the plurality of gate lines (GL)in the active area (A/A), through the gate driving portion 210.

The data signal line 141 b may be formed in the lower end non-activearea (N/A), between the data driving portion 230 and the data line (DL)in the active area (A/A). The data signal lines 141 b may output datasignals provided from the data driving portion 230 to the plurality ofdata lines (DL) in the active area (A/A).

The light-emitting signal line 141 c may be formed in the non-activearea (N/A), between the data driving portion 230 and the light-emittingcontroller 220. The light-emitting signal line 141 c may output alight-emitting signal provided from the data driving portion 230, to thelight-emitting controller 220. The light-emitting signal may be outputto the plurality of sensing lines (SL) in the active area (A/A), by thelight-emitting controller 220.

In the flexible OLED display device 200 according to the secondembodiment of the present invention, the lower end non-active area (N/A)may include a bending area (B/A). The bending area (B/A) may be a regionwhich has a predetermined curvature when part of the lower endnon-active area (N/A) is bent to the front or rear surface of theflexible OLED display device 200.

The lower end non-active area (N/A) may be divided, for example, intothree regions by the bending area (B/A). For instance, the lower endnon-active area (N/A) may be divided into a first area between thebending area (B/A) and the active area (A/A), the bending area (B/A),and a second area between the bending area (B/A) and an area where thedata driving portion 230 has been mounted.

The first area of the lower end non-active area (N/A) may be a regioncovered by a bezel portion, etc., together with the rest of thenon-active area (N/A). Also, the second area may be a region positionedon the rear surface of the flexible OLED display device 200, by bendingof the bending area (B/A).

The plurality of data signal lines 141 b and the plurality of powerlines may be formed in the first area. The plurality of power linesinclude the second driving voltage line 146 b, the second referencevoltage line 147 b and the second ground line 145 b. The plurality ofdata signal lines 141 b may be connected to the plurality of data lines(DL) in the active area (A/A). The plurality of data signal lines 141 band the plurality of power lines may be formed in the first area inparallel with each other.

In the bending area (B/A) of the lower end non-active area (N/A), theplurality of data signal lines 141 b and the plurality of power linesformed in the first area, may be formed in parallel with each other.

In the bending area (B/A) of the lower end non-active area (N/A), theplurality of lines extending from the power lines toward the active area(A/A), the plurality of data signal lines 141 b, the gate signal lines141 a and the light-emitting signal lines 141 c may be formed so as tobe spaced from each other on the same layer on the flexible substrate110.

In the second area of the lower-end non-active area (N/A), signal linesincluding the gate signal lines 141 a, the data signal lines 141 b andthe light-emitting signal lines 141 c may be formed to cross powerlines. The power lines, which may have a bar shape, may include firstand second driving voltage lines 146 a, 146 b, first and secondreference voltage lines 147 a, 147 b, and first and second ground lines145 a, 145 b. The signal lines and the power lines in the second areamay be formed to overlap each other on different layers on the flexiblesubstrate 110.

The signal lines and the power lines may be formed to be in parallel toeach other in the first area and the bending area (B/A), by being bentat least twice in the second area.

That is, in the flexible OLED display device 200 according to the secondembodiment, a plurality of signal lines and a plurality of power linesmay be formed to cross each other in the second area positioned on therear surface of the flexible OLED display device 200 when the bendingarea (B/A) of the lower end non-active area (N/A) is bent toward therear surface of the device 200. Thus, in the flexible OLED displaydevice 200 according to the second embodiment, the width of the lowerend non-active area (N/A) can be more reduced than in the conventionalflexible OLED display device. As a result, the flexible OLED displaydevice 200 according to the second embodiment can have a narrow bezelportion.

As mentioned above, in the flexible OLED display device 200 according tothe second embodiment, a plurality of signal lines and a plurality ofpower lines are formed on the same layer in parallel to each other, inthe bending area (B/A) of the lower end non-active area (N/A).Accordingly, unlike in the conventional art, disconnection of the wirescan be prevented even if an insulating layer is damaged due to bendingstress.

In the first area and the bending area (B/A) of the lower end non-activearea (N/A), wires are formed on the same layer in accordance with oneembodiment of the invention. However, in the second area, wires may beformed on different layers. Based on this configuration, wires formed ondifferent layers in the second area may be connected to wires formed onthe same layer in the bending area (B/A), through holes (not shown).

FIG. 9 is a cross-sectional view taken along line in the flexible OLEDdisplay device of FIG. 8.

Referring to FIGS. 8 and 9, in the bending area (B/A) of the lower endnon-active area (N/A) of the flexible OLED display device 200, aplurality of wires may be formed on the same layer in a spaced mannerfrom each other.

For instance, in the bending area (B/A), a passivation layer 111 isformed on a flexible substrate 110. A gate signal line 141 a, a datasignal line 141 b, a second ground line 145 b and a second drivingvoltage line 146 b may be formed on the passivation layer 111, such thatthey are spaced from each other with predetermined distances, inparallel to each other.

A first insulating layer 117 a may be formed on the gate signal line 141a, the data signal line 141 b, the second ground line 145 b and thesecond driving voltage line 146 b.

A plurality of wires may be formed to overlap each other on differentlayers, in the second area positioned on the rear surface of theflexible OLED display device 200 when the bending area (B/A) of thelower end non-active area (N/A) is bent.

For instance, in the second area, a passivation layer 111 is formed on aflexible substrate 110. A gate signal line 141 a and a data signal line141 b may be formed on the passivation layer 111, such that they arespaced from each other in parallel to each other.

A first insulating layer 117 a may be formed on the gate signal line 141a and the data signal line 141 b. A second ground line 145 b and asecond driving voltage line 146 b may be formed on the first insulatinglayer 117 a, with a predetermined distance therebetween in parallel toeach other. In this case, the second ground line 145 b and the seconddriving voltage line 146 b may be formed to overlap the gate signal line141 a and the data signal line 141 b.

A second insulating layer 117 b may be formed on the second ground line145 b and the second driving voltage line 146 b.

In the flexible OLED display device 200 according to the secondembodiment, the pixel region in the active area (A/A) has the samecross-sectional profile as the pixel region described above withreference to FIG. 6, of which description is not repeated.

A plurality of wires formed in the non-active area (N/A) may be formedof the same metallic material as a source electrode (not shown) and adrain electrode (not shown) in the pixel region, at the same processingstage. The plurality of wires indicate power lines including the secondground line 145 b and the second driving voltage line 146 b, and signallines including the gate signal line 141 a and the data signal line 141b. For instance, the plurality of wires may be formed of a metallicmaterial such as Ti, Al and Mo or an alloy thereof such as Ti/Al/Ti andMo/Al.

FIG. 10 is a view illustrating a wire structure in a bending area in aflexible OLED display device according to the present invention, andFIG. 11 is a view illustrating various embodiments of FIG. 10.

In this embodiment, the flexible OLED display device 100 of FIG. 4 willbe explained for convenience. However, this embodiment may be alsoapplicable to the flexible OLED display device 200 of FIG. 8.

Referring to FIGS. 4 and 10, in the flexible OLED display device 100,wires may be formed to have a large width for prevention ofdisconnection thereof due to bending stress in the bending area (B/A) ofthe lower end non-active area (N/A).

For instance, as shown in FIG. 10, the width (d2) of wires in thebending area (B/A) of the lower end non-active area (N/A) may be greaterthan the width (d1) of wires in the first area and the second area ofthe lower end non-active area (N/A).

As shown in FIG. 11, wires are formed, in the bending area (B/A), with ashape such as a triangle, a diamond, a semi-circle and a circle. Thus,disconnection of the wires, due to bending stress occurring when thebending area (B/A) is bent, can be prevented.

That is, in the flexible OLED display device 100, disconnection ofwires, which occurs when the bending area (B/A) is bent, can beprevented by various shape changes of the wires in the bending area(B/A). In order to prevent resistance increase of the wires due to theshape changes of the wires, the wires may be formed such that the widthin the bending area (B/A) is larger than that in the other regions. As aresult, disconnection of the wires, which occurs when the bending area(B/A) is bent, can be prevented.

The aforementioned wires may be power lines including the first groundline 145 a and the first driving voltage line 146 a, and signal linesincluding the gate signal line 141 a and the data signal line 141 b.

The foregoing embodiments and advantages are merely exemplary and arenot to be considered as limiting the present disclosure. The presentteachings can be readily applied to other types of apparatuses. Thisdescription is intended to be illustrative, and not to limit the scopeof the claims. Many alternatives, modifications, and variations will beapparent to those skilled in the art. The features, structures, methods,and other characteristics of the exemplary embodiments described hereinmay be combined in various ways to obtain additional and/or alternativeexemplary embodiments.

As the present features may be embodied in several forms withoutdeparting from the characteristics thereof, it should also be understoodthat the above-described embodiments are not limited by any of thedetails of the foregoing description, unless otherwise specified, butrather should be considered broadly within its scope as defined in theappended claims, and therefore all changes and modifications that fallwithin the metes and bounds of the claims, or equivalents of such metesand bounds are therefore intended to be embraced by the appended claims.

What is claimed is:
 1. A display device comprising: a first substrate including an active area, a bending area, and a pad area; a plurality of pixels to display an image in the active area, each of the plurality of pixels including an organic light emitting diode (OLED); a signal line and a power line disposed on the first substrate, the signal line and the power ling being disposed on a same layer in the bending area, the bending area on the first substrate being configured to be bent flexibly; and a second substrate facing the active area and disposed on the first substrate.
 2. The display device of claim 1, wherein the signal line includes at least one of a gate line to supply a gate signal to each of the plurality of pixels and a data line to supply a data signal to each of the plurality of pixels, and wherein the power line includes at least one of a driving voltage line to supply a driving voltage to the corresponding OLED, a reference voltage line to supply a reference voltage to the corresponding OLED, and a ground voltage line.
 3. The display device of claim 1, wherein the signal line and the power line are spaced apart from each other in the bending area.
 4. The display device of claim 3, wherein the signal line and the power line are formed in parallel with each other in the bending area.
 5. The display device of claim 1, wherein the signal line and the power line do not overlap each other in the bending area relative to a viewpoint from a front side toward a back side of the display device.
 6. The display device of claim 1, wherein the signal line and the power line are formed on different layers outside the bending area.
 7. The display device of claim 1, wherein a width of the signal line in the bending area is greater than a width of the signal line outside the bending area, and wherein a width of the power line in the bending area is greater than a width of the power line outside the bending area.
 8. The display device of claim 1, wherein at least one of the signal line and the power line is formed in a non-straight form in the bending area.
 9. The display device of claim 1, wherein the signal line and the power line are formed of a same material.
 10. The display device of claim 1, wherein each of the plurality of pixels includes a switching transistor connected to the signal line and configured to supply the signal to the corresponding OLED, and a driving transistor connected to the power line and configured to supply the power to the corresponding OLED, and wherein an output of the switching transistor is connected to a gate of the driving transistor.
 11. The display device of claim 1, wherein the signal line and the power line are commonly formed on a flexible substrate in the bending area.
 12. The display device of claim 11, wherein the signal line is formed on the flexible substrate, and the power line is formed on an insulation layer overlying the signal line outside the bending area.
 13. The display device of claim 1, wherein the signal line and the power line are disposed on different layers to overlap each other in the pad area adjacent to the bending area. 